1. Field of the Invention
The present invention is broadly concerned with a novel road deicer composition which is significantly more effective than salt while being substantially less expensive than other non-salt substitute deicers such as calcium magnesium acetate. More particularly, the invention pertains to a novel road deicer in the form of a solid particulate and including in preponderant amount calcium magnesium propionate; the deicer composition is preferably obtained by the fermentation of sugars with P. acidi-propionici to yield a mixture of organic acids (predominantly propionic acid) which is thereafter reacted with a source of calcium and magnesium cations such as dolomite.
2. Description of the Prior Art
The importance of the effectiveness removal of snow and ice from roadways during winter can not be overemphasized in terms of reducing traffic accidents and fatalities. Approximately eight million metric tons of salts, principally sodium chloride and some calcium chloride, are used annually on roadways in the United States for this purpose. While these salts are inexpensive and effective deicers, there are numerous harmful effects attendant to their use. These include the accelerated corrosion of automobiles, degradation of structural and reinforcing steel, damage to roadside vegetation, and harm to drinking water supplies. Among the various alternative compounds heretofore proposed as substitute deicers, calcium magnesium acetate (CMA) has emerged as the leading candidate, based on its effectiveness in deicing and reducing corrosion rates and environmental effects. However, the cost of this product is approximately twenty times or more than that of rock salt. Therefore, the use of CMA by various local and state governmental agencies has been quite minimal owing to cost considerations.
CMA is produced by reacting dolomite with acetic acid. Dolomite is relatively inexpensive, and the major cost factor in the production of CMA is the cost of raw material, acetic acid. The large scale production of a deicer such as CMA from synthetic acetic acid is not economically feasible at present. The annual requirement of acetic acid would be above twice the annual production levels of this chemical, just to substitute 10% of the rock salt consumption with CMA.
The most economical route currently developed envisaged for the production of acetic acid is via the conversion of biomass-derived sugars by anaerobic fermentation using the obligate anaerobe C. thermoaceticum. However, anaerobic fermentation requires optimal operating temperatures of 55.degree.-60.degree. C., a pH of 7-8, and the maintenance of a completely oxygen-free reaction environment. These conditions necessitate the use of rather expensive equipment and procedures, and hence production costs are still relatively high. Furthermore, acid production using C. thermoaceticum is limited at sugar concentrations higher than about 2%. Thus, if a 10% sugar solution is used, only 2% is utilized for acid production. This not only limits the production of acid, but moreover means that a higher proportion of water must be removed to obtain a dry product, thus further increasing production costs.